How Much Fault Protection is Enough - A Deep Impact Perspective

For the deep impact project, a myriad of fault protection (FP) monitors, symptoms, alarms and responses is engineered into the spacecraft FP software, common and yet custom to the flyby and impactor mother-daughter spacecraft. Device faults and functional faults are monitored, which are mapped 1-to-n into FP symptoms, per instance of the fault. Symptoms are then mapped n-to-1 to FP alarms, further down mapped n-to-1 to FP responses. Though the final statistics of 49 monitors, 921 symptoms, 667 alarms, and 39 responses appear to be staggering, it remains debatable whether the amount of on-board autonomous fault protection is sufficient and friendly to operate